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3

Erm, I think your problem is that "jewel" doesn't have an opposite, unless you count "paste". Can you give some sense of what quality of jewels you're trying to evoke the opposite of?
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ChristiApr 27 '12 at 20:06

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People, people, people: not all words have antonyms. It's a fact of English and a fact of life.
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RobustoApr 27 '12 at 20:09

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It depends on context, I suppose. Jewels have a number of distinctive characteristics: hardness, clarity, brilliance, intrinsic value... Change any one of them, and you have the opposite. In chemistry, the flame of a burning gas can be described as "gem-like"; in fact, the phrase is used to describe ignited flatulence. So perhaps the opposite of "jewel-like" is "like an unlit fart"?
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MT_HeadApr 27 '12 at 20:11

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As MT_Head points out, without further context this question is impossible to answer. Opposites are defined by context. Man can be the opposite of woman, or the opposite of boy, or the opposite of animal — even though a man is an animal (and not a plant). So, please provide further context, then this question can be reopened. Otherwise the most helpful answer we can offer is jewel-unlike, which is not really helpful at all.
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RegDwigнt♦Apr 27 '12 at 20:19

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When you say you want the opposite of "someone with attractive qualities", should that mean "someone with a lack of attractive qualities", or "someone with UNattractive (ugly, repellent, repulsive,...) qualities"? Because those two could be very different.
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FrustratedWithFormsDesignerApr 27 '12 at 21:18

4 Answers
4

I'm going to suggest "banal" as an answer to this question. A banal person would be someone who generally makes one feel worse for time in their company. If you're looking for a word which specifically conveys lack of value, "worthless" is also a possibility.

I've not heard gem-like used of people, but I assume OP means something akin to she's/he's a gem, which are both common enough. The sense there is that she/he is a valuable person - well worth knowing because they have fine personality traits (not because they have wealth). The "antonym" would thus be someone who isn't worth knowing...

My favorite is "a waste of carbon", which can be interpreted in several ways; in this context, it could mean "instead of being wasted on your useless carcass, that carbon could have been used to make a diamond!"
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MT_HeadApr 27 '12 at 21:47